For many years, the county put up a “ROAD CLOSED” sign just before the first switchback. You could easily drive around it. If you did, you might get a ticket, especially if you were in the way when they started clearing rocks in the spring. If you got stuck, they wouldn’t dig you out, and your car might be there until spring, when you would probably also get a ticket.
A few years ago, they put up a lockable gate at the same location. I understand that they sometimes lock the gate and sometimes just put up the sign. Maybe someone will chime in with more information.